Executive function (EF), also referred to as fluid cognition, is comprised of working memory, inhibitory control, and attention shifting processes known to be dependent upon cortical circuitry associated primarily with the prefrontal cortex and to develop rapidly in early childhood. As a unique aspect of developing cognitive competence with a well-defined neurobiological basis, EF has been shown to play a central role in developing aspects of self-regulation important for social and academic competence and readiness for school. However, given the relation of EF to the development of self-regulation, there is currently no uniform measurement battery that can reliably and validly measure individual differences in change in EF in early childhood. There is an urgent need to develop such a measurement battery, particularly for use in the context of large-scale studies. Its absence limits knowledge of basic developmental questions regarding intraindividual change in EF and the relation of that change to the primary accomplishments of early childhood. Accordingly this application proposes to develop an easily administered, highly portable battery of working memory, inhibitory control, and attention shifting cognitive tasks to measure EF in 3 to 5 year old children;to utilize item response theory to establish the psychometric properties and scoring procedures for the measurement battery in a cross sectional sample of 300 children age 3 to 5 years;to collect data on developmental change using the EF battery with a racially and economically diverse, epidemiologically derived sample of 600 children that are being followed from birth to age 3 in a study known as the Family Life Project and that will be followed from ages 3 to 5 years under this application to create a normative database for the newly developed EF measurement battery;and to establish the validity of the EF measurement battery with the normative sample of 600 by determining the extent to which performance on the battery accounts for unique variance over and above that associated with general intelligence and language ability in standardized laboratory and teacher and parent report measures of social and academic competence and emotional reactivity and effortful control, and by determining the extent to which the battery identifies EF deficits in low severity/high incidence developmental disorders such as learning disability and attention deficit-hyperactivity disorder.